textproduct: Rapid City

KEY MESSAGES

- Elevated to critical fire weather conditions expected for Thursday.

- Cold front moves through later Thursday, bringing rain/snow behind it.

- Warming trend over the weekend with mostly dry conditions Saturday through middle of next week.

UPDATE

Issued at 942 PM MDT Wed Apr 15 2026

Upper level analysis shows 500hpa wave/trof east of the Dakotas with abundant convection firing from OK northeast through OK/AR,IL into WI and MI. Upper flow has turned SW over the region as next closed 500hpa low/long-wave trof drops into Pac NW. Noted earlier in the evening a few lightning strikes in ID as lead wave ejects out ahead of this system. At the surface, weak surface low pressure is located across western SD as noted in surface wind field and earlier returns on the KUDX radar. Temps at 03z are still fairly mild, generally in the mid 50s to lower 60s with winds 15 mph or less. Mid to high level cloudiness is streaming over the area in the SW flow aloft. Overnight lows in the mid 40s to around 50 still look to be on track.

Critical to near critical fire weather conditions still look to be in store for Thursday across our southern and south central zones, as gusty southwest to west winds set up along with above seasonal temps and low relative humidity. There is some question now about the cold frontal timing, as it appears to be slowing down ever so slightly when compared to earlier runs, but by only 3 or so hours at most. This may be an issue with onset of pcpn probabilities as well as reach of fire weather conditions. Relative humidities still fall into the mid teens during the afternoon hours across the Red Flag Warning area, so right now see no reason to alter. As the cold front comes through, widespread pcpn still looks favorable with many places seeing at least 0.05, and possibly up to 0.35 or higher QPF. Deterministic models are continue to show a favored snow belt from northeast WY, northern Black Hills and into northwest SD. As previous fcst stated, snow amounts are tricky after warm period, how much sticks to ground and how long it actually snows. Will continue to forego any winter wx headlines attm.

Main area of pcpn will move out during the day on Friday, however temps will remain chilly in the Friday and Saturday time frame. Sunday will see some warmer weather return ahead of a more unsettled pattern returning for next week.

DISCUSSION

(This Evening Through Wednesday) Issued at 1230 PM MDT Wed Apr 15 2026

Current surface analysis shows high pressure over southeastern SD, with a weak surface trough stretching from northwest SD down into eastern Wyoming. Upper air analysis depicts shortwave over NE/KS region, upper low over the PAC NW, with near west/east flow over the forecast area. Temperatures currently sit in the 60s to low 70s, with light winds. Recent satellite images show mid/high clouds expanding into the forecast area from the west.

Elevated to near-critical fire weather parameters continue this afternoon, as warm and dry conditions persist. Thursday will see some areas reach critical fire weather conditions ahead of a cold front, as temperatures reach into the 70s and low 80s, with winds 15 to 25 mph, and gusts up to 40 mph in the late morning and afternoon. Cold front moves through from northwest to southeast Thursday afternoon into the evening, bringing gusty northwest winds and chances for rain/snow through mid-day Friday. Any accumulating snow amounts will be tricky given the time of year, and temperatures hanging near freezing for some areas. Highest potential for accumulating snowfall is expected in parts of northeastern Wyoming into the central and northern Black Hills, where NBM probability of 2" or more ranges between 30 to 70 percent. Widespread light QPF is expected, with the highest ranges (0.05" - 0.4") stretching from northeastern WY into northwestern SD. Current model runs show a small potential for low end Winter Weather Advisory headline for some areas Thursday night, but again chances are small. Main precipitation event moves out mid-day Friday, but some light precipitation could linger for some areas (generally Black Hills into southwest SD) into Saturday.

After this system moves through, mostly dry conditions return late Saturday through middle of next week. Upper ridge builds over the western CONUS through the weekend as well, resulting in a warming trend back to 10-20F above normal. Longer range models point to the potential for more active weather the latter half of next week, but will have to wait and see how model agreement works out.

AVIATION

(For the 18Z TAFS Through 18Z Friday) Issued At 1120 AM MDT Thu Apr 16 2026

A cold front will continue moving through the area this afternoon/early evening. It is about to cross the KRAP terminal (16/18z) now. Behind the cold front as an upper level disturbance approaches, expect an expanding area of MVFR/IFR CIGS as low clouds slide southeast through tonight. A band of rain changing to snow will develop with IFR VSYBS from K2WX to KSPF to KGCC common tonight. Isolated TS may occur this afternoon. Gusty north winds will develop just east of the Black Hills (~45kt gusts) this evening, tailing off Friday morning. Conditions will slowly improve from northwest to southeast Friday, especially after the current TAF period.

FIRE WEATHER

Issued At 1230 PM MDT Wed Apr 15 2026

Elevated fire weather conditions continue this afternoon across much of the area as RH falls into the teens to low 20s. Best overlap of low RH and stronger winds forecast across southern Campbell and Weston Counties in WY through southwestern SD. Conditions remain below thresholds for any fire weather highlights today.

A Red Flag Warning has been issued for Thursday for the Weston County plains through southern SD as stronger southwest winds will develop ahead of a cold front. Daytime minimum RH will fall as low as 12-14 percent Thursday. Timing of the cold front as well as mid-level clouds ahead of the front and spotty high- based showers may complicate things a bit by keeping temperatures a bit cooler and RH higher. However, plan for at least elevated to near- critical conditions Thursday.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Red Flag Warning until 7 PM MDT /8 PM CDT/ this evening for SDZ321-322-325-326-332>335. WY...Red Flag Warning until 7 PM MDT this evening for WYZ317.